Cut the Tempeh into 1/2" cubes. Place in a saucepan along with the water, Tamari, garlic and ginger slices.
Bring to a boil, reduce heat and simmer 10 minutes. Drain.
Heat oil in a saute pan over medium heat. Add Tempeh and fry until golden brown. Remove from pan and keep warm.
In the same saute pan, heat oil over medium heat and add garlic and shallots, stirring continuously until the shallots are soft, about 3 minutes.
Add the mushrooms and salt and saute until mushrooms are soft, about 4 minutes more.
Add marsala and the remaining tablespoon oil.
Meanwhile, dissolve Arrowroot in soy milk. Slowly add the soy milk to the marsala mixture, stirring constantly, and cook over low heat until thickened.
Place Tempeh cubes onto plates and spoon sauce over tempeh.